scholarly journals Transfer of methods for determining parameters of self‐loosening for tests on the vibration test bench according to Junker to tests on a newly developed test setup for single‐bolted joints with short clamping length using an axial test bench

Author(s):  
A. Eberhard ◽  
S. Beyer ◽  
M. Klein ◽  
M. Oechsner
2017 ◽  
Vol 3 (1) ◽  
Author(s):  
Imam Maolana

The goal of this work is to design and build a vibration test bench to simulate unbalance in rotating machine. The vibration test bench made of a 25 mm diameter steel shaft and length of 410 mm supported by two ball bearings. Two steel discs to variate unbalance load installed in the shaft powered by 0.5 Hp electric motor with maximum rotation of 1400 RPM. Inverter used to control rotation from electric motor. Vibration testing conducted at two condition; (1) without load and rotation variation, (2) unbalance load with variation of unbalance mass. Pick up point of vibration measurement at bearing house in radial and axial direction. The vibration parameter measured are amplitude and spectrum (wave form). Amplitude measurement using hand held vibrometer, while spectrum using accelerometer conected to a Data Acquisition. After testing the condition using unbalance load, we conclude that the vibration test bench match unbalance condition as described in theory which is high amplitude at machine frequency, and it’s value proportional to unbalance mass. We find that the highest amplitude is at horizontal direction where machine stiffnes is smallest. Vibration testing with no load condition show that there is harmonic in vibration spectrum indicating rotating looseness, probably caused by bearing wear. 


Author(s):  
Jia Zhang ◽  
◽  
Jinghan Wen ◽  
Ye Song ◽  
Pingbo Wu

In order to avoid the additional influence on the test results caused by the inconsistency between the boundary conditions of the carbody and the reality when using the vibration exciter or hammer to test the free mode of the carbody, a 6-DOF vibration test bench is tried to simulate the actual motion posture of the carbody to test its modal parameters. For in-depth discussion, a full-scale virtual prototype of the 6-DOF vibration test bench was built, and on this basis, the test bench-carbody rigidflexible coupling virtual test system was established. According to the modal frequency range of the carbody to be tested and the actual load capacity of the test bench, the excitation frequency and amplitude of the test bench are determined. Through the virtual modal test, it is determined that the carbody should be elastically supported when testing the modal parameters of the carbody by using the vibration test bench, so as to accurately obtain the modal parameters of the carbody.


2021 ◽  
Vol 7 (1) ◽  
Author(s):  
Thore von Steuben ◽  
Christoph Salewski ◽  
Alexander B. Xepapadeas ◽  
Moritz Mutschler ◽  
Sebastian Spintzyk

Abstract Background During cardiogenic shock blood circulation is minimal in the human body and does not suffice to survive. The extracorporeal life support system (ECLS) acts as a miniature heart-lung-machine that can be temporarily implanted over major vessels e.g. at the groin of the patient to bridge cardiogenic shock. To perform this procedure in an emergency, a proper training model is desirable. Therefore, a 3-dimensional-printable (3D) material must be found that mimics large vessel needle penetration properties. A suitable test bench for material comparison is desirable. Methods A test setup was built, which simulated the clinically relevant wall tension in specimens. The principle was derived from an existing standardized needle penetration test. After design, the setup was fabricated by means of 3D printing and mounted onto an universal testing machine. For testing the setup, a 3D printable polymer with low Shore A hardness and porcine aorta were used. The evaluation was made by comparing the curves of the penetration force to the standardized test considering the expected differences. Results 3D printing proved to be suitable for manufacturing the test setup, which finally was able to mimic wall tension as if under blood pressure and penetration angle. The force displacement diagrams showed the expected curves and allowed a conclusion to the mechanical properties of the materials. Although the materials forces deviated between the porcine aorta and the Agilus30 polymer, the graphs showed similar but still characteristic curves. Conclusions The test bench provided the expected results and was able to show the differences between the two materials. To improve the setup, limitations has been discussed and changes can be implemented without complications.


2012 ◽  
Vol 232 ◽  
pp. 445-449 ◽  
Author(s):  
Florian Liebold ◽  
Stephan Wiegand ◽  
Ronny Käso

Structural stability of satellites is of vital significance for the operation of sophisticated payload systems. Therefore manufacturers of satellite components, such as reaction wheels, make huge efforts to assure the convenient vibration behavior of their products. To meet that demand a device for the detection of mechanical oscillations with very small amplitudes was developed. The described micro-vibration test-bench allows the detection of vibrations with amplitudes > 10 5 Newton in a frequency range of < 20 kHz generated by a test item with a mass up to 30 kg. The quality of the thereby obtained data makes it possible to identify the sources of the observed vibration. The high information content of the measurements originates from a set of high resolution force sensors, variably arranged on a mechanically isolated platform. The sensitivity of the used equipment (charge cables, charge amplifiers and signal analyzers) and its resistance to ambient disturbances allow the high accuracy of the measurement as mentioned above. The described micro-vibration test-bench additionally provides opportunity to detect production errors non-destructively and helps to reduce the inherent noise of the item under test. It therefore represents a reliable measurement device to quantify and assess detrimental vibrations.


2011 ◽  
Vol 101-102 ◽  
pp. 1151-1155
Author(s):  
Mei Zi Tian ◽  
Deng Feng Zhao ◽  
Guo Ying Zeng ◽  
Hang Rui Yan

Based on the vibration mechanics theory and system’s state equation, the state-space model of the flange bolted-joints structure is established. According to the dynamic characteristics of bolted connection, the parameters of the state-space model, such as rigidity and damping, can be identified. The accuracy of simulation model is validated, by comparing the simulation analysis results with the vibration test results, and an efficient method of recognition or fault diagnosis of bolted joints in vibratory environment is proposed.


Author(s):  
Laurianne Delcor ◽  
Etienne Parizet ◽  
Julie Ganivet-Ouzeneau ◽  
Julien Caillet

Vibrations contribute to helicopter’s ride comfort. This study aimed to determine the relationship between main rotor vertical excitations and discomfort. Fifty-three participants, seated on a helicopter seat fixed to a vibration test bench, evaluated the discomfort of vertical sinusoidal vibrations using a magnitude estimation procedure. Stimuli had a frequency between 15 and 30 Hz and a level between 0.32 and 3.16 m/s2. The average discomfort was shown related to vibration velocity using Steven’s power law, without any frequency dependence. The exponent depended on velocity and was 1.18 for higher velocities (approx. above 0.008 m/s) and 0.65 for velocities below that limit.


Author(s):  
Luis Pascual ◽  
Santiago Pasalodos ◽  
Jose Ignacio Bueno ◽  
Marcos Ubierna ◽  
Antonio Gonzalez-Elias

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